The compound .alpha.-chloro-.alpha.-oximino-4-hydroxyacetophenone is a well known compound having the structural formula (Formula 1): ##STR1## The compound is known to have good anti-bacterial and germicidal properties. Accordingly, it is used as an industrial biocide to control the growth of bacteria and microorganisms which develop in water-based media used in the manufacture of various industrial products. The discovery of the antibacterial and germicidal properties of the compound is described in British Patent No. 1,290,646.
When used as an industrial biocide, .alpha.-chloro-.alpha.-oximino-4-hydroxyacetophenone is used in association with a suitable vehicle. Suitable vehicles include water, alcohol, hydrocarbons and other organic solvents as well as mineral, animal and vegetable oils. The compositions typically contain about five (5) to about twenty (20) percent by weight of the active ingredient.
Several methods have been employed in the past for the preparation of .alpha.-chloro-.alpha.-oximino-4-hydroxyacetophenone. Levin et al. 7 Journal of Organic Chemistry, 408 (1942), discloses the preparation of the compound by reacting hydroxyphenacyl chloride with isopropyl nitrite in the presence of hydrogen chloride. One disadvantage of that method is that hydroxyphenacyl chloride is expensive and difficult to handle. Furthermore, hydroxyphenacyl chloride is a strong lachrymator and causes severe dermatitis.
U.S. Pat. No. 4,910,338 discloses the preparation of .alpha.-chloro-.alpha.-oximino-4-hydroxyacetophenone by reacting 4-hydroxyacetophenone with an alkyl nitrite and hydrogen chloride wherein the amount of hydrogen chloride is carefully controlled to limit the amount thereof to about 0.1 to six moles of hydrogen chloride per mole of 4-hydroxyacetophenone until at least one equivalent of the alkyl nitrite is reacted. Subsequent to the reaction of the one equivalent of alkyl nitrite, at least one mole of hydrogen chloride per mole of initially charged 4-hydroxyacetophenone is added to the reaction medium. One disadvantage of that process is that it utilizes alkyl nitrites. The handling of those compounds is undesirable because they are potential explosives. Furthermore, another disadvantage of that process is that it generates alcohols because of the presence of the isopropyl nitrite. The isopropyl alcohol causes the generation of undesirable byproducts such as p-hydroxyphenylglyoxal acetals.
In U.S. Pat. No. 3,794,620 there is disclosed a process for the preparation of a general class of aromatic carbonyl hydroxamoyl chlorides by the reaction of aromatic acetyl derivatives with nitrosyl chloride. These chlorides are alleged to be useful as cross-linking, chain-extending, and/or capping agents for unsaturated polymers or polymers containing mercaptan groups. One of the disadvantages of this process is the fact that the reaction temperatures in the overall reaction medium increase substantially and in an uncontrolled manner.
The present invention discloses a process which substantially reduces the difficulties of the prior art processes. The process utilizes starting materials which are more economical than the starting material of the prior art processes, eliminates the handling of potentially explosive material such as alkyl nitrites, reduces the formation of undesirable by-products, and substantially reduces and controls the reaction temperatures.
These and other objects and advantages of the present invention will become apparent from the following description.